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严重气道阻塞患者常发生动态肺过度充气,此因肺排气过程延长,呼吸系容量在还没有达到松弛的静态平衡时,呼气即被下1次吸气所打断,导致了呼气末弹性回缩正压的存在,称之为‘内在’或‘自发’PEEP。自主呼吸患者‘内在’PEEP(PEEPi)的存在,提示吸气肌必须产生足够的力,以克服吸气流开始前的弹性回缩正压,故 PEEPi 的存在相当于吸气屏气负荷的作用,导致呼吸功和氧耗的增加。本研究观察严重 COPD 患者在撤离机械通气时应用持续正压通气(CPAP)对呼吸方式、呼吸功和呼吸困难的影响,及其对减少由 PEEPi 诱发的机械负荷的能力.严重 COPD 患者7(男6、女1)例,年龄42～75岁,均因急性呼衰行机械通气,病情稳定12～24小时能忍受自主呼吸至少30分钟后接受本研究。所有患者均取半卧位,撤机予以自主呼吸,分别给予5、10、15cmH_2O 的 CPAP 2～5分钟,同时监测各项指标。结果所有的病人在机械通气时存在 PEEPi,平均9.9±1.1cmH_2O。加用 CPAP 后,随着 CPAP水平的增加,潮气量(V_T)不变,食管压和跨隔压进
Patients with severe airway obstruction often occur in dynamic lung hyperinflation, due to prolonged exhaust process of the lungs, respiratory system capacity has not yet reached the relaxation of the static equilibrium, the expiratory is interrupted by the next inhale, resulting in exhaled The presence of a late-stage elastic retraction positive pressure is referred to as ’intrinsic’ or ’spontaneous’ PEEP. The presence of PEEPi in spontaneously breathing patients suggests that the inspiratory muscle must produce sufficient force to overcome the elastic recoil positive pressure before the inspiratory flow begins, so the presence of PEEPi is equivalent to the suction breath-hold load, Resulting in increased respiratory work and oxygen consumption. This study examined the effects of continuous positive airway pressure (CPAP) on respiratory pattern, respiratory work, and dyspnea in patients with severe COPD evacuated from mechanical ventilation and their ability to reduce the mechanical load induced by PEEPi.7 Severe COPD patients7 6, female 1) cases, aged 42 to 75 years, were mechanically ventilated due to acute respiratory failure and were stable in 12 to 24 hours to tolerate spontaneous breathing for at least 30 minutes after receiving this study. All patients were taken semi-recumbent, weaning to be spontaneous breathing, were given 5,10,15cmH_2O CPAP 2 to 5 minutes, while monitoring the indicators. Results All patients had PEEPi at mechanical ventilation with an average of 9.9 ± 1.1cmH_2O. With CPAP, with the increase of CPAP level, the tidal volume (V_T) unchanged, esophageal pressure and across the pressure into